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Typically, peak travel seasons coincide with holidays and school breaks, when the kids are off and families are able to travel together.

However, for those without young children, avoiding these times of year can help lead to cheaper flights and fewer crowds of tourists.

"The summer travel high season ends right after Labor Day weekend," Tom Spagnola, the SVP of supplier relations at CheapOair, told Business Insider. "The fall low season, which ends around Thanksgiving holiday travel, offers some great opportunities to save, as airlines compete to drive up sales. Throughout August, we expect to see airlines continue to load in attractive fall fares."

With that in mind, CheapOair sorted through its data to find some of the most popular hot spots that millennials are traveling to this fall — especially places other than the traditional big cities.

"These are a bit different than some of the usual hot spots we see, but they're all trending up, especially among the millennial set," said Spagnola. "For the most part, these are travelers who are looking for experiences that are less the tourist trap of high-priced restaurants and shopping."

Plenty of deals are still available for these spots, including traditional hotel lodging and Airbnbs. Scroll down to see the hottest places for off-peak travel this fall, and click through to find some great deals.

Keep in mind that the listed average fares represent what CheapOair's customers have paid so far for travel to these destinations during these months. As airlines continue to load lower fall fares into their pricing, it's very possible that you'll find lower pricing.

Liverpool, England

Although airfare is a bit pricier in September and October than it is in August, Liverpool is generally a calmer — and cheaper — city than London, making it a perfect destination for those looking to get outside the capital.

According to Spagnola, Liverpool has been trending especially up lately, with good food, great nightlife, and tons of possible day trips.

Tip: To save on flights, consider flying into London or Manchester and taking a train to Liverpool. Be sure to compare flight prices.

Montreal, Canada

With tons of hiking, plenty of music, and fantastic restaurants, Montreal has a perfect mix of cosmopolitan culture and great outdoors. With a robust Airbnb scene and plenty of hotels, lodging should be easy to sort out on any budget.

Montreal and other destinations in Canada have been particularly appealing, according to Spagnola, as a new low-cost airline, Swoop, owned by Canadian airline WestJet, have driven prices down.

"Fares to several Canadian markets from the US are as much as 50% lower than what we saw last year, as other airlines have dropped their fares to compete," he said.

Home to trendy restaurants, tons of art galleries, museums, and plenty more, Portland is ideal during the fall. Take some time to visit nearby breweries or wineries, and head outside of the city for some great hiking and mountain biking — Multnomah Falls makes an easier, nearby hiking route, and Ecola State Park has routes near the beach.

Phuket, Thailand

Muzhik/Shutterstock

Average airfare from the US:

August: $1,527.29

September: $845.73

October: $674.65

Thailand is rapidly becoming one of the hottest destinations, so this fall is your chance to get in before it gets even more popular. Phuket offers interesting shops and incredible cuisine, and you can spend the rest of your trip exploring pristine beaches and breathtaking villages and country spots. Plus, Thailand is relatively budget-friendly (once you're there).

Tip: If you're planning on exploring the country and aren't set on the city, check out flights to Bangkok as well — compare flight prices to find the best deal.

Ann Arbor, Michigan

Airfare is pretty consistent across late-summer and early-fall, and since it's a domestic flight, prices are fairly reasonable. Ann Arbor, home to the sprawling University of Michigan campus, features all types of activities, from college football games to wandering through more than 30 independent bookshops.

Xi'an, China

TripAdvisor

Average airfare from the US:

August: $775.13

September: $1,014.59

October: $603.69

Xi'an's rich history and vibrant culture offer a great place to kick off an exploration of a few different spots within China. Xi'an is home to the famous Terra Cotta Army, and features tons of restaurants and museums. Airfare is generally similar to Beijing and Shanghai, but it can vary, so you may want to compare flights to all three cities — especially if you plan to visit all of them.

Los Angeles, California

From tranquil beaches to some of the world's hottest nightclubs — not to mention some of the best Mexican food in the world — Los Angeles has something for everyone. Soak up the sun, keep an eye out for some celebs, and kick back and enjoy.

Lisbon, Portugal

MoveHub

Average airfare from the US:

August: $832.98

September: $905.04

October: $761.34

Portugal is an increasingly popular destination, and according to CheapOair, more millennials are heading there from the US than ever. Between pristine beaches, winding city streets, and historical ruins, Lisbon has something for everyone.

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